Typical exothermic heat-generating pads are disclosed in a variety of patents issued within the last 15 years or so.
Generally, such products contain an exothermic composition such as a composition of iron powder, active carbon, salt, sawdust, water, and other components. Those components are normally blended to provide an exothermic chemical reaction when exposed to air. The components generate heat which may be exploited to warm various parts of the body.
The exothermic composition may be contained within a porous, breathable bag composed of a woven fabric. The porous bag is normally stored within a nonventilating plastic outer bag. When the outer bag is opened, the contents of the porous bag are exposed to air, thereby activating the exothermic properties of the components contained within.
Typical patents relating to such exothermic heat-generating packets or pads include, by way of example, U.S. Pat. Nos. 3,976,049; 4,268,272; and 4,282,005. Each patent relates generally to the same type of end product, but discloses a different combination of exothermic heat-generating ingredients. Such products will produce heat for a period of between 12 and 24 hours at temperatures up to 160.degree. F., and can be provided in a variety of different sizes deemed to be convenient for application to the body. Such products have been advantageously used by a variety of sports enthusiasts who are exposed to frigid air, as well as by the general public, for example, in keeping warm during outdoor sporting events such as football games and the like.
Such products may be contained in the pockets of outer garments or in shoes or boots and so forth. Unfortunately, outer garments, shoes, boots, and the like do not always provide the most efficient means for receiving such exothermic heating pads, and clearly, they do not provide convenient means for wearing such pads adjacent certain joints or extremities for warming or therapeutic purposes.
Alternatively, hats, headbands, and earmuffs are known which provide only protection and thermal insulation to the wearer's head. It is commonly known that a large percentage of a human being's body heat escapes through the head area. To protect against hypothermia in cold activities, headgear is commonly recommended. However, this headgear generally provides only a passive heat insulation which merely limits the amount of heat allowed to escape.
Additionally, devices are known which provide temperature therapy to different areas of the head. Examples are U.S. Pat. Nos. 3,491,761; 3,796,855; 4,190,054; and 4,204,543. However, none of these devices provide a system for applying an active warming element in combination with nonobtrusive headgear which may be used by enthusiasts engaged in sports environments where hypothermia might be experienced.